1. Field of the Invention
The present invention relates to a double-faced liquid crystal display device and a mobile telecommunication terminal using the same.
2. Description of the Related Art
A related art liquid crystal display device will be described with reference to the accompanying drawings.
FIG. 1 is a sectional view showing a related art liquid crystal display device, and FIG. 2 is a schematic view showing a double-faced display device based on the related art liquid crystal display device.
As shown in FIG. 1, the related art liquid crystal display device includes a lower substrate 13, an upper substrate 12, and a liquid crystal 14. The lower substrate 13 includes a scan electrode pattern, a signal electrode pattern, and a pixel electrode pattern. The upper substrate 12 includes a common electrode pattern, a black matrix, and a color filter layer. The liquid crystal 14 is implanted between the upper substrate 12 and the lower substrate 13.
Polarizers 11 and 15 are respectively disposed on the upper substrate 12 and below the lower substrate 13 to compensate a phase difference due to refraction of light when characters, numbers or figures are displayed. A reflector 16 is disposed on the bottom of the polarizer 15 to reflect light.
The upper substrate 12 and the lower substrate 13 between which the liquid crystal 14 is implanted are formed of glasses or films having excellent transmittivity of light. The electrode patterns formed in the upper substrate 12 and the lower substrate 13 may be of dot matrix types, segment types, or a mix of dot matrix and segment types.
In some applications, it is desirable to provide a double-faced display; that is, a display that can be viewed from two faces, or surfaces. One example of such an application is a folding cover type mobile telecommunicative terminal such as a cellular telephone. In this type of application, it is desirable to have a double-faced display with one display viewable on the inside of the folding cover for displaying information when the phone is in use by a user, and a second display viewable on the outside of the cover, which allows information such as caller identification information to be displayed to a user without requiring the user to open the phone.
The construction of a related art double-faced display device for displaying characters, numbers and/or figures on two faces using two conventional liquid crystal display devices of the type discussed above will now be described.
As shown in FIG. 2, the related art double-faced display device includes first and second liquid crystal display devices 26a and 26b having respectively, signal electrodes and scan electrodes, a controller 21 for analyzing an input video signal and outputting a control signal for displaying characters, numbers or figures, a first memory 22 comprising a volatile memory device, for temporarily storing an input signal and storing booted data to promptly process the operation of the controller 21, a second memory 23 comprising a nonvolatile memory device, for storing an operational algorithm of the controller 21, a first driver 24a for driving the signal electrodes and the scan electrodes of the first liquid crystal display device 26a in accordance with a control signal of the controller 21 to display a video signal, a second driver 24b for driving the signal electrodes and the scan electrodes of the second liquid crystal display device 26b in accordance with the control signal of the controller 21 to display a video signal, and first and second frame memories 25a and 25b for storing signals for displaying characters, numbers or figures, applied from the first and second drivers 24a and 24b. 
In other words, in a conventional double-faced display, there are provided two liquid crystal display devices having separate signal electrodes and scan electrodes, and two drivers for, respectively, the two liquid crystal display devices.
The operation of the conventional double-faced display device, in which one liquid crystal display device is attached on a front face and a second liquid crystal display device is attached on a rear face, will now be described.
When power is supplied to the system, the controller 21 accesses an operation program stored in the second memory 23 and detects the signals for displaying externally input characters, numbers or figures in a state that the system is initially booted.
At this time, if the externally input signals are detected, the controller 21 analyzes the input signals through the operational algorithm and analysis program set in the first and second memories 22 and 23 and applies the control signal for displaying characters, numbers or figures to the first and second drivers 24a and 24b. 
The first and second drivers 24a and 24b apply a driving signal for displaying corresponding characters, numbers or figures to the scan electrodes and the signal electrodes of the first and second liquid crystal display devices 26a and 26b attached on inner and outer surfaces of the system for double-faced display, so that the same characters, number or figures can respectively be displayed on the first and second liquid crystal display devices 26a and 26b. 
At this time, the first and second frame memories 25a and 25b process and store the control signal applied from the controller 21 for a frame. Then, the first and second frame memories 25a and 25b output the frame signal stored in corresponding memory areas in accordance with access signals of the first and second drivers 24a and 24b, so that corresponding characters, numbers or figures can stably be displayed on the first and second liquid crystal display devices 26a and 26b. 
However, the related art double-faced display device has several drawbacks.
First, to display characters, numbers or figures on two faces, two liquid crystal display devices must separately be provided. To drive the two liquid crystal display devices, two drivers corresponding to the two liquid crystal display devices must be provided. To simultaneously display two faces, a duplicated control algorithm is used. This increases power consumption and thus increases the production cost.
Furthermore, since the two drivers are provided to drive the two liquid crystal display devices, a large area is required in the system. This makes it difficult to produce a light-weight and slim-sized product. For example, in a folding cover type mobile telecommunication terminal, in order to display identification information for a calling party without opening the folding cover, two liquid crystal display devices must be provided, one attached on an inner face of the cover and the other on the outer face of the cover. This makes a light-weight and slim-sized folding cover type mobile telecommunication terminal difficult. Also, since the expensive liquid crystal display devices and drivers are additionally provided, the cost of the terminal increases.
Accordingly, the present invention is directed to a liquid crystal display device and a mobile telecommunication terminal using the same that substantially obviates one or more of the limitations and disadvantages of the related art.
An object of the present invention is to provide a double faced liquid crystal display device and a mobile telecommunication terminal using the same, in which one liquid crystal display device displays information on two faces so that messages such as caller identification information, a received message, and temporal (e.g., time and date) information can be displayed even when a folding cover is not open.
Another object of the present invention is to provide a liquid crystal display device and a mobile telecommunication terminal using the same, in which production costs can be saved and a slim-sized and light-weight mobile telecommunication terminal can be achieved.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages in accordance with the present invention, as embodied and broadly described herein, a liquid crystal display device according to the present invention includes a first substrate having a common electrode, a second substrate having n scan electrodes and m signal electrodes, a liquid crystal layer disposed between the first and second substrates, a polarizer, and a reflector, wherein the liquid crystal display device is divided into a first region and a second region, and the polarizer and the reflector are symmetrically disposed so that the first region is displayed in a first direction and the second region is displayed in a second direction.
In another aspect, a liquid crystal display device includes a first substrate, a second substrate disposed below the first substrate, a liquid crystal layer disposed between the first substrate and the second substrate, a first front polarizer disposed above and extending over a first portion of the first substrate, a first rear polarizer disposed above and extending over a second portion of the first substrate, a first reflector disposed above the rear polarizer and extending over the second portion of the first substrate, a second rear polarizer disposed below and extending under a first portion of the second substrate, a second reflector disposed below the second rear polarizer and extending under the first portion of the second substrate, and a second front polarizer disposed below and extending under a second portion of the second substrate.
In other aspect, a mobile telecommunication terminal includes a folding cover movable between an open position and a closed position, having a window in a predetermined area, a liquid crystal display device having a first region and a second region, the first and second regions being displayed to oppose each other, and the liquid crystal display device being mounted an inner side of the folder cover to externally display the second region through the window, and a driver for driving the liquid crystal display device.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.